Electricity is a modern day necessity. Any building or home built today in the United States is wired for electricity. In wiring these homes and buildings, electric receptacles are placed throughout the building and are typically located on the lower section of walls. Once these homes and buildings are occupied furniture often must be placed in front of a receptacle. The occupant is often faced with the dilemma of either placing the furniture several inches out from the wall so that the receptacle can be accessed for use or placing the furniture flush against the wall, thus leaving the receptacle inaccessible for use.
This problem is compounded when the occupant has an appliance which has a grounded plug and the receptacle is ungrounded.
One possible option in the past has been the use of an extension cord. However, extension cords can be a fire hazard and a trip hazard in certain applications. They also present unsightly clutter.
Other adaptors have been presented to solve this problem however they typically are rather complicated devices with moving parts which increase the likelihood of failure of the adaptor.
Addressing the issue of plugging the grounded plug into the ungrounded receptacle, the occupant has had one of three unsatisfactory options to solve this problem. The first option would be to cut off the grounding prong on the plug, however this leaves the appliance ungrounded and thus presents a danger of electrocuting the occupant.
The second option would be to employ an adaptor plug which has a ground wire extending from it. The grounded appliance plug is simply inserted into the female end of the adaptor. The adaptor is then plugged into the receptacle and the grounding wire is secured to the grounding screw on the face of the receptacle. While this does allow for grounding of the appliance, the extra step of having to unscrew and then reattach grounding screw with the grounding wire is inconvenient as many times the occupant does not have a screw driver handy. Also as the adaptor ages the coating on the grounding wire can become brittle and break and the wire can become frayed thus creating a danger of electrocution and/or fire.
The third option would be to use an adaptor plug having a metal grounding tab extending parallel with the male face of the adaptor. This operates in much the same way as the adaptor described above. The grounded appliance plug is inserted into the female end of the adaptor. The plug can then be inserted into the ungrounded receptacle. In order to provide grounding, the grounding screw on the receptacle must be removed and used to secure the grounding tab to the receptacle. In addition to having the same drawbacks as the adaptor with the grounding wire the adaptor with a grounding tab can only provide grounding when used in the top receptacle. If the adaptor is inserted in the bottom receptacle the grounding tab extends in the direction opposite the receptacle grounding screw.
The other draw back of using either one of these adaptors is that they cause the plug to stick out further from the wall, typically 1″ to 1½″ thus further complicating the location of furniture in front of the receptacle.